1. Field of the Invention
This invention relates to a process for the incineration of sewage sludge and refuse. Sewage sludge from municipal or industrial sewage systems is preferably desiccated and then incinerated in conjunction with a refuse incinerator.
2. Background Information
Known processes for the harmless disposal of sewage sludge attempt to solve sewage disposal problems by means of drying the sludge and then incinerating the sludge. For example, German Laid Open Patent Application No. 35 42 004 discloses a process for drying sewage sludge with heated exhaust from a clinker cooling system during the manufacture of cement clinker. The process disclosed is specifically tailored to cement production. In addition, the sewage sludge, dried in a separate process stage, is fed as fuel into the sintering furnace.
Another example of a disposal process can be found in German Patent No. 36 35 068, which discloses a process for the detoxification of contaminated material as part of a degasification process which includes indirect heating. In this process, whereby the degasification stage involves indirect heating, the drying and incineration of contaminated material do not occur in the same process stage.
German Laid Open Patent Appln. No. 39 10 215 discloses a process for the drying and incineration of sewage sludge at a coal-fired power plant. Here, too, drying and incineration do not occur in the same process stage. The vapors are incinerated in the zone where the firing takes place and the dried sludge is added to the coal to be burned. Drying takes place indirectly using condensing steam. The vapors from the drying of the sewage sludge increase the flue gas volume during the burning of the coal.
Thus, a process in which the drying, carbonization and incineration of sewage sludge occur in one single process stage is not known. Further, it has been found that such a unified sewage treatment process can be suitable for the formation of reduction agents that are generally necessary for the removal of nitrogen which forms during refuse incineration. It is this combination of sewage treatment and refuse incineration that accounts for the success of the process according to the present invention.